1. Technical Field
The present invention relates to a brake system or a retarder having a blower which picks up energy from a power transmission line of a vehicle and uses the energy to drive the blower, thereby applying a brake force to the vehicle, and particularly to a brake system which cuts off the energy from the power transmission line for the sake of safety when trouble occurs in the brake system.
2. Background Art
Generally, large vehicles such as a large bus or truck are equipped with an auxiliary brake system in addition to a main brake system (e.g., a foot brake) since they need a large braking force to stop. Fluid retarders and electrical retarders are well known in the art as the auxiliary brake system for the vehicle. However, these retarders generate a considerable amount of heat due to the energy conversion during braking. Therefore, a device for cooling a working medium is required. The cooling device raises the cost of the auxiliary brake system and makes the arrangement complicated.
On the other hand, the assignee of the present invention has developed another type of auxiliary brake system, namely a "Turbo Retarder," which is disclosed in Japanese Patent Application No. 62-136476. This application teaches a brake system employing a blower which is connected to the crankshaft of the engine via a clutch and a speed change mechanism. The blower is driven by the crankshaft and consumes energy from the engine, thereby applying a brake force to the engine. This arrangement does not require a device for cooling a working medium. However, if the gears of the speed change mechanism break or a seizure occurs in the bearings of the speed change mechanism, a duly large force is applied to the crankshaft. This might result in damage to the crankshaft or other members coupled with the crankshaft and, in turn, breakdown of the vehicle.